JP2006091260A - Lens driving apparatus and digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact lens driving apparatus which controls position by detecting the original point of a lens and to provide a digital camera in which the lens driving apparatus is used. <P>SOLUTION: A reflection member 70 is provided around the outer periphery of a lens holder 45 and the reflectance of the reflection member is different from that of the surrounding part. An aperture 41b is formed on an upper cover 41 at a position facing to the reflection member 70 when the lens holder 45 is located at the original point which is an approaching end. Further, an optical position detection means PR71 is provided next to the aperture 41b on the upper cover 41. The PR71 optically detects the reflection member 70 via the aperture 41b when the lens holder 45 arrives at the original point. Thus the original point of the photographing lens 23 is detected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lens driving device that detects the origin position of a lens and controls the lens position, and a digital camera using the lens driving device.

  In recent years, digital cameras have been widely used in general. Such a digital camera has been reduced in size and weight in order to improve portability. In addition, it is widely performed that a digital camera is mounted on a small device such as a mobile phone or a PDA (Personal Digital Assistant). In such a case, it is necessary to further reduce the size and weight of the digital camera. For this reason, it has been desired to reduce the size of a lens driving device used in a digital camera.

In order to solve such a problem, a lens driving device using a hollow stepping motor is known (for example, see Patent Document 1). Such a lens driving device includes a lens holder for holding a lens, a hollow rotor provided so as to cover the outer periphery of the lens holder, and a stator provided so as to cover the outer periphery of the hollow rotor. The hollow rotor is rotated by supplying a pulse current to the lens holder, and the lens holder is moved back and forth in the optical axis direction by a cam mechanism or the like. For this reason, it is possible to reduce the size of the lens driving device by integrating the stepping motor and the lens barrel.
JP 60-417

  In the lens driving device, it is important to detect the origin position of the lens in order to control the position of the lens with high accuracy. Optical position detection means such as a photo interrupter (hereinafter referred to as PI) is provided. The origin position of the lens was detected. However, the lens driving device described in Patent Document 1 does not have a space for installing an optical detection means such as PI, and attempts to detect the origin position using an optical position detection means such as PI. There is a problem that the lens driving device is enlarged.

  The present invention has been made in view of the above circumstances, and a small lens driving device capable of detecting the origin position of a lens and controlling the lens position with high accuracy, and a digital using the lens driving device. The purpose is to provide a camera.

  In order to solve the above problems, a lens driving device of the present invention has a cylindrical shape, is arranged to cover a lens holder that holds a lens, and an outer periphery of the lens holder, and the optical axis of the lens is the center. In the lens driving device, comprising: a rotating cylinder that is rotated; and a holding member that rotatably holds the rotating cylinder from the outer peripheral side, and the lens holder is moved forward and backward in the optical axis direction by the rotation of the rotating cylinder. A reflection member provided on an outer periphery of the holder and having a reflectance different from that of the periphery; an opening formed on the holding member; and disposed at a position facing the reflection member when the lens holder is at an origin position; and the opening And an optical position detecting means for optically detecting the reflecting member through the opening when the lens holder reaches the origin position. The one in which the features.

  In addition, when the reflecting member is covered by the rotating cylinder when the lens holder is at the origin position, it is preferable that an opening is formed in the rotating cylinder at a position facing the reflecting member.

  A stator that is held by the holding member and has a cylindrical shape and that forms a magnetic field in the cylindrical shape, and a magnet that is provided on the outer periphery of the rotating cylinder and has a cylindrical shape, is formed by the stator. The rotating cylinder is rotated by a magnetic field.

  In order to solve the above problems, a digital camera of the present invention acquires image data by capturing a subject image formed by the lens driving device according to any one of claims 1 to 3 and the lens. An image pickup means and a storage means for storing the image data picked up by the image pickup means are provided.

  According to the lens driving device and the digital camera of the present invention, since it is only necessary to provide the reflecting member inside the holding member, an optical position detecting means such as PI is arranged inside the holding member, and the origin position of the lens The lens driving device and the digital camera can be reduced in size as compared with the case of detecting. Moreover, since it is only necessary to provide an opening in the holding member, the strength of the holding member is not impaired.

  In the present embodiment, an example in which the lens driving device of the present invention is applied to a camera-equipped mobile phone will be described. FIG. 1 is an external perspective view showing the configuration of the front side of the camera-equipped mobile phone 10, and FIG. The camera-equipped mobile phone 10 includes an upper housing 11, a lower housing 12, and a hinge portion 13 that rotatably connects these housings 11 and 12.

  The casings 11 and 12 are formed in a substantially rectangular thin plate shape. The upper housing 11 and the lower housing 12 are centered on the hinge portion 13 and the open position shown in FIGS. 1 and 2 and the closed position where the upper housing 11 and the lower housing 12 are folded so as to be substantially parallel to each other. It is rotated between.

  An LCD panel 21 and a reception speaker 22 are provided on the front surface 11a of the housing 11, and a photographing lens 23 is exposed on the back surface 11b. An antenna 24 is provided on the upper surface 11c. The LCD panel 21 displays various menu screens, various information such as the telephone number of the called party, and images. The receiving speaker 22 outputs the voice of the other party, and the antenna 23 transmits and receives voice data and radio wave signals such as e-mail.

  On the front surface 12a of the lower housing 12, an operation unit 31 and a transmission microphone 32 are provided. Further, the lower surface 12b of the lower housing 12 is provided with a slot 35 into which a storage medium such as a memory card is loaded. The operation unit 31 includes various operation buttons such as a selection key 31a and a shutter button 31b. When the photographer operates the selection key 31a to select a photographing mode from a plurality of modes, the camera-equipped mobile phone 10 becomes ready for photographing. Further, the transmission microphone 32 converts the sound into an electrical signal.

  Further, the above-described photographing lens 23 is moved forward and backward along the optical axis direction by a lens driving device incorporated in the upper housing 11. Hereinafter, the configuration of the lens driving device will be described with reference to FIGS. FIG. 3 is an external perspective view showing the configuration of the lens driving device 40. 4 is a cross-sectional view of the lens driving device 40 when the photographing lens 23 is extended to the near end, and FIG. 5 is a cross-sectional view of the lens driving device 40 when the photographing lens 23 is retracted to the infinite end. It is.

  The lens driving device 40 includes an upper cover 41 and a lower cover 42 that are holding members, a stator 43 that is sandwiched between the upper cover 41 and the lower cover 42, and a rotating cylinder 44 that is disposed inside the stator 43. The lens holder 45 is disposed inside the rotating cylinder 44 and holds the photographing lens 23. Further, the stator 43, the rotating cylinder 44, and the lens holder 45 are integrally stored by the upper cover 41 and the lower cover 42, and the lens driving device 40 is unitized.

  The lower cover 42 holds a low-pass filter 46 and a CCD 47 that is an imaging means. The low-pass filter 46 and the CCD 47 are disposed behind the taking lens 23, and the low-pass filter 46 removes high-frequency components contained in the subject light. For this reason, the subject light transmitted through the photographing lens 23 is incident on the CCD 47 via the low-pass filter 46, and problems such as false colors and moire can be reduced. Further, although the low-pass filter 46 and the CCD 47 are described as being held by the lower cover 42, they may be provided outside the lens driving device 40.

  A cylindrical magnet 49 is provided on the outer peripheral surface of the rotating cylinder 44. Below, the structure of the stator 43 and the magnet 49 is demonstrated. As shown in FIG. 6, the stator 43 includes a first coil part 50 and a second coil part 60. The first coil unit 50 includes a cylindrical coil 51 around which a conductive wire is wound, an upper coil cover 52, and a lower coil cover 53. These coil covers 52 and 53 are arranged on the outer peripheral surface side. And it is provided so that it may cover from the inner peripheral surface side, and the whole 1st coil part 50 is made into the cylindrical shape.

  A plurality of teeth 52 a and 53 a formed on the upper coil cover 52 and the lower coil cover 53 are arranged on the inner peripheral surface side of the first coil portion 50 so as to engage with each other alternately. Further, these teeth 52a and 53a are arranged with a gap so as not to contact each other. For this reason, when a current flows through the coil 51, the teeth 52a and 53a are poled to have opposite polarities.

  Although the first coil unit 50 has been described above, the second coil unit 60 has the same configuration, and includes a coil 61, an upper coil cover 62, and a lower coil cover 63. The upper coil cover 62 has a plurality of teeth 62a, and the lower coil cover 63 has a plurality of teeth 63a. The second coil unit 60 is arranged such that the teeth 62a and 63a are shifted by a half pitch with respect to the teeth 52a and 53a of the first coil unit 50.

  Further, a pulse current is alternately supplied to the coils 51 and 61. For example, when a pulse current is supplied in the forward direction to the coil 51 with the direction indicated by the arrow A in the figure as the forward direction, the coil 51 is rotated clockwise (clockwise) with respect to the direction in which the pulse current flows. The magnetic field is generated. Thereby, the magnetic field lines are guided from the upper coil cover 52 toward the lower coil cover 53. At this time, the lines of magnetic force are guided from the upper coil cover 52 to the lower coil cover 53 via a gap (in the air), so that the teeth 52a become the N pole and the teeth 53a become the S pole. Similarly, when a pulse current is supplied to the coil 61 in the forward direction, the tooth 62a becomes the N pole and the tooth 63a becomes the S pole.

  Further, when a pulse current is supplied to the coil 51 in the reverse direction, a magnetic field in the direction opposite to that when the pulse current is supplied in the forward direction is generated around the coil 51. At this time, the lines of magnetic force are guided from the lower coil cover 53 to the upper coil cover 52 through a gap (in the air), so that the tooth 52a is an S pole and the tooth 53a is an N pole. Similarly, when a pulse current is supplied to the coil 61 in the reverse direction, the tooth 62a becomes the S pole and the tooth 63a becomes the N pole. As described above, when a pulse current is supplied to the coil 51 and the coil 61, N-pole and S-pole magnetic fields are alternately formed on the inner circumferences of the first coil unit 50 and the second coil unit 60.

  The magnet 49 has a cylindrical shape having an outer diameter smaller than the inner periphery of the stator 43. The magnet 49 is a permanent magnet whose outer periphery is alternately poled into N poles and S poles, and has 48 poles. The magnet 49 rotates with respect to the stator 43 by repulsive force and attractive force with a magnetic field formed on the inner periphery when a pulse current is supplied to the stator 43. The magnet 49 rotates with the rotation angle for one pole as one step, and rotates once in 48 steps.

  Next, the control of the pulse current for each rotation direction of the magnet 49 will be described. Similar to the direction of the pulse current, the direction indicated by the arrow A in the figure will be described as the forward direction of the rotation of the magnet 49. First, the case where the magnet 49 is rotated in the forward direction will be described.

  When rotating the magnet 49 in the forward direction, the pulse current is repeatedly supplied in the order of the forward direction of the coil 51, the forward direction of the coil 61, the reverse direction of the coil 51, and the reverse direction of the coil 61. Thereby, the N pole is formed in the order of the teeth 52a, the teeth 62a, the teeth 53a, and the teeth 63a, and at the same time, the S pole is formed in the order of the teeth 53a, the teeth 63a, the teeth 52a, and the teeth 62a. An attractive force and a repulsive force act on the N pole and S pole of the magnet 49 between the teeth 52a, 53a, 62a, and 63a, and the magnet 49 rotates in the forward direction.

  When rotating the magnet 49 in the reverse direction, the pulse current is repeatedly supplied in the order of the forward direction of the coil 51, the reverse direction of the coil 61, the reverse direction of the coil 51, and the forward direction of the coil 61. Thereby, the N pole is formed in the order of the teeth 52a, the teeth 63a, the teeth 53a, and the teeth 62a, and at the same time, the S pole is formed in the order of the teeth 53a, the teeth 62a, the teeth 52a, and the teeth 63a. An attractive force and a repulsive force act on the N pole and the S pole of the magnet 49 between the teeth 52a, 53a, 62a, and 63a, and the magnet 49 rotates in the reverse direction.

  When the magnet 49 is rotated as described above, the rotating cylinder 44 is rotatably held by the upper cover 41 and the lower cover 42, so that the rotating cylinder 44 rotates integrally with the magnet 49. A helicoid 44 a that is a spiral groove is formed on the inner peripheral surface of the rotating cylinder 44.

  Below, the structure of the lens holder 45 is demonstrated. As shown in FIG. 7, the lens holder 45 includes a cylindrical main body tube 45a and a cylindrical front tube 45b that is integrally formed in front of the main body tube 45a and has an outer diameter smaller than that of the main body portion 45a. It is configured. A helicoid 45c that is screwed with the helicoid 44a of the rotating cylinder 44 is formed on the outer peripheral surface of the main body cylinder 45a. Further, three key grooves 45d parallel to the optical axis direction are formed on the outer periphery of the front cylinder 45b. The keyway 45d is engaged with a rectilinear key 41a which is a protrusion provided on the upper cover 41. For this reason, when the rotating cylinder 44 rotates, the lens holder 45 is prevented from rotating by the rectilinear key 41a and moves forward and backward in the optical axis direction.

  Further, as described above, the lens holder 45 holds the photographing lens 23 inside, and the photographing lens 23 is composed of three lenses, a first lens 23a, a second lens 23b, and a third lens 23c. It is configured. For this reason, the lens holder 45 is moved back and forth in the optical axis direction by the rotation of the rotating cylinder 44, and the position of the photographing lens 23 is changed to the near end position (position shown in FIG. 4) and the ∞ end position (position shown in FIG. 4). (Position shown in FIG. 5). The rotating cylinder 44 rotates twice while the photographic lens 23 moves from the close end position to the ∞ end position. Further, the lens driving device 40 detects the origin position of the photographing lens 23 in order to control the position of the photographing lens 23. Hereinafter, detection of the origin position of the photographing lens 23 will be described.

  A reflection member 70 is provided at the lower part of the outer peripheral surface of the front cylinder 45b. The surface of the reflecting member 70 is, for example, a mirror surface. Further, since the lens holder 45 is made of, for example, black resin or the like, the surface of the reflection member 70 has a reflectance different from that of the periphery thereof.

  Further, an opening 41b is formed on the side wall of the upper cover 41 at a position facing the reflection member 70 described above when the photographing lens 23 is at the close end position (position shown in FIG. 4). Further, a photo reflector (hereinafter referred to as PR) 71 which is an optical position detecting means is provided so as to be adjacent to the opening 41b. A PR is a light emitting element and a light receiving element arranged in parallel in the same direction or at a predetermined angle and housed in one package. By detecting the reflected light of the light emitted from the light emitting element, the PR It is an optical sensor that detects presence or absence and position.

  PR71 is a reflection member that reflects the difference in reflectivity through the opening 41b when the photographing lens 23 is moved to the close end position that is the origin position, that is, when the lens holder 45 is extended to the position shown in FIG. 70 is detected optically. That is, when the lens holder 45 is extended forward in the optical axis direction and the photographing lens 23 is moved to the close end (position shown in FIG. 4), the PR 71 detects the origin position and outputs a detection signal.

  As described above, since the reflecting member 70 only needs to be provided on the outer periphery of the lens holder 45, an optical position detecting means such as PI is provided inside the upper cover 41 and the lower cover 42 in order to detect the origin position of the photographing lens 23. The lens driving device 40 can be reduced in size compared to the case where the lens driving device 40 is provided. Further, since it is only necessary to form a part of the opening 41b in the upper cover 41, the strength of the upper cover 41 does not decrease.

  Next, the electrical configuration of the camera function of the camera-equipped mobile phone 10 will be described. FIG. 8 is a block diagram showing an electrical configuration of the camera function. The system controller 80 is control means for controlling the entire mobile phone 10 with camera. A selection key 31a and a shutter button 31b are connected to the system controller 80. When the selection key 31a is operated by the user, the system controller 80 executes processing corresponding to each operation. For example, when the selection key 31a is operated and the photographing mode is set, the system controller 80 controls each unit so that photographing can be performed. Further, when the shutter button 31b is operated by the user, the system controller 80 controls each unit to execute shooting processing.

  The CCD 47 captures the subject image formed by the photographing lens 23 and acquires image data. An image processing circuit 81 is connected to the CCD 47 and outputs image data to the image processing circuit 81. An image memory 82 is connected to the image processing circuit 81, and image data is stored in the image memory 82. The image processing circuit 81 converts analog image data into digital image data when image data is stored in the image memory 82, and performs various correction processes such as brightness level correction and white balance correction, YC processing, Compression processing or the like is performed on the image data.

  When a through image is displayed on the LCD panel 21, the image processing circuit 81 performs various correction processes on the image data, and then performs a simple YC process to obtain YC image data composed of luminance data and color difference data. Convert. The YC image data is transmitted from the image memory 82 to the display circuit 83, converted into a composite signal such as NTSC by the display circuit 83, and output to the LCD panel 21.

  When shooting is performed, the image processing circuit 81 performs various correction processes on the image data, and then performs YC processing to generate YC image data. The YC image data is further subjected to compression processing and converted into compressed image data in, for example, JPEG format.

  A memory controller 84, a coil driver 85, PR 71, and an AF evaluation value calculation circuit 86 are connected to the system controller 80. The system controller 80 controls the memory controller 84 to store the above-described compressed image data in the memory card 87.

  Further, the system controller 80 outputs a drive signal to the coil driver 85 to generate a pulse current. The coil driver 85 supplies a pulse current to the coil 51 and the coil 61 to move the photographing lens 23 forward and backward in the optical axis direction as described above.

  The PR 71 outputs a detection signal to the system controller 80 when the photographing lens 23 moves to the origin position. In addition, a pulse counter 80 a that counts the number of pulse currents supplied to the coil 51 and the coil 61 is provided inside the system controller 80. The system controller 80 resets the pulse counter 80 to “0” when acquiring this detection signal. The system controller 80 controls the position of the photographing lens 23 by outputting a drive signal to the coil driver 85 based on the count data of the pulse counter 80a.

  The AF evaluation value calculation circuit 86 acquires image data of a predetermined area in the shooting screen from the image processing circuit 81, and calculates an AF evaluation value based on the contrast of the image data. The contrast of the image is highest when the subject image is in focus. At this time, the AF evaluation value is also highest. The AF evaluation value calculation circuit 86 sends an AF evaluation value signal corresponding to the AF evaluation value to the system controller. Output to 80. The system controller 80 moves the photographing lens 23 to the in-focus position by controlling the position of the photographing lens 23 based on the AF evaluation value signal.

  Next, photographing processing of the camera-equipped mobile phone 10 will be described using the flowcharts of FIGS. The system controller 80 determines whether or not the shooting mode is set. If the shooting mode is not set, the system controller 80 maintains the camera function in the OFF state. When the photographing mode is set, the system controller 80 turns on the camera function, that is, activates each part constituting the camera function, and then performs origin detection processing.

  Next, the origin position detection process will be described. The system controller 80 determines whether a detection signal is output from the PR 71. If it is determined that the detection signal is output, the photographing lens 23 is at the origin position, and the pulse counter 80a is also reset, so the origin detection process is terminated.

  When it is determined that the detection signal is not output, the photographing lens 23 is moved toward the proximity end (position shown in FIG. 4). At this time, the system controller 80 repeatedly determines whether or not a detection signal is output from the PR 71. When it is determined that the detection signal is not output, the photographing lens 23 is further moved toward the proximity end, and when it is determined that the detection signal is output, the movement of the photographing lens 23 is stopped. . Thereafter, the pulse counter 80a is reset and the origin position detection process is terminated.

  When the origin detection process ends, the focus position detection process of the photographic lens 23 is performed. The system controller 80 acquires an AF evaluation value signal from the AF evaluation value calculation circuit 86 while controlling the coil driver 85 to move the photographing lens 23 forward and backward in the optical axis direction. The system controller 80 controls the coil driver 85 based on the AF evaluation value signal and the count data of the pulse counter 80a to move the photographing lens 23 to the in-focus position.

  The system controller 80 determines whether or not the shutter button 31b is half-pressed. When it is determined that the shutter button 31b is not half-pressed, the focus position detection process of the photographing lens 23 is repeatedly performed until the shutter button 31b is half-pressed. When it is determined that the shutter button 31b is half-pressed, the photographing lens 23 is fixed at the in-focus position and focus locked.

  Thereafter, the system controller 80 determines whether or not the shutter button 31b is fully pressed. When the shutter button 31b is released without being fully pressed, the focus lock is released and the focus position detection process is performed again. When the button is fully pressed, the system controller 80 controls the memory controller 84 to store the image data in the memory card 87.

  Thereafter, the system controller 80 ends the shooting process when the mode is switched to a mode other than the shooting mode, and performs the focus position detection process again when the shooting mode is maintained.

  In the present embodiment, the case where the close end position of the photographic lens 23 is set as the origin position has been described as an example. However, the present invention is not limited to this, and the ∞ end position of the photographic lens 23 may be set as the origin position. In this case, when the reflecting member 70 is disposed at the rear end of the outer peripheral surface of the main body cylinder 45b and the photographing lens 23 is moved to the ∞ end position, an opening is formed at a position corresponding to the reflecting member 70 of the lower cover 42, What is necessary is just to arrange | position PR71 so that it may adjoin to this opening.

  Further, when the reflecting member 70 is provided at a position covered by the rotating cylinder 44 when the photographing lens 23 is at the origin position, an opening may be formed at a corresponding position of the rotating cylinder 44. In this case, the PR 71 optically detects the reflecting member 70 through the opening 41 b and the opening formed in the rotary cylinder 44. Furthermore, although it has been described that the reflecting member 70 is provided on the outer periphery of the lens holder 45, the present invention is not limited to this, and a reflecting surface having a different reflectance may be formed on a part of the outer peripheral surface of the lens holder 45 by plating or the like. good.

  Furthermore, in the present embodiment, the lens driving device 40 using a hollow stepping motor has been described as an example. However, the present invention is not limited to this, and a normal stepping motor or a DC motor is used, and the rotating cylinder 44 is connected via a gear train. It may be rotated.

  In the present embodiment, the case where the present invention is applied to a camera-equipped mobile phone has been described as an example. However, the present invention is not limited to this, and the present invention may be applied to a normal digital camera.

It is an external appearance perspective view which shows the structure of the front side of the mobile phone with a camera. It is an external appearance perspective view which shows the structure of the back side of the mobile phone with a camera. It is an external appearance perspective view which shows the structure of a lens drive device. It is sectional drawing which shows the structure of a lens drive device. It is sectional drawing which shows the structure of a lens drive device. It is a perspective view which shows the structure of a stator and a magnet. It is a perspective view which shows the structure of a lens holder. It is a block diagram which shows the electrical structure of the camera function of the mobile telephone with a camera. It is a flowchart explaining an imaging | photography process. It is a flowchart explaining an origin detection process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mobile phone with camera 23 Shooting lens 40 Lens drive device 41 Upper cover 41b Opening 42 Lower cover 43 Stator 44 Rotating cylinder 45 Lens holder 70 Reflective member 71 PR

Claims (4)

A lens holder that has a cylindrical shape and holds the lens, is arranged so as to cover the outer periphery of the lens holder, and rotates around the optical axis of the lens, and the rotating tube is rotatable from the outer peripheral side. A lens driving device that moves the lens holder forward and backward in the direction of the optical axis by rotation of the rotating cylinder,
A reflection member provided on the outer periphery of the lens holder, and having a reflectance different from that of the surrounding;
An opening formed in the holding member and disposed at a position facing the reflecting member when the lens holder is at the origin position;
An optical position detecting means provided adjacent to the opening, and optically detecting the reflecting member through the opening when the lens holder reaches an origin position. Drive device.   The opening of the rotating cylinder is formed at a position facing the reflecting member when the reflecting member is covered by the rotating cylinder when the lens holder is at the origin position. Lens drive device.   A stator that is held by the holding member and has a cylindrical shape and that forms a magnetic field in the cylindrical shape, and a magnet that is provided on the outer periphery of the rotating cylinder and has a cylindrical shape, is formed by the stator. The lens driving device according to claim 1, wherein the rotating cylinder is rotated by a magnetic field. The lens driving device according to any one of claims 1 to 3, an imaging unit that captures a subject image formed by the lens and acquires image data, and the image data captured by the imaging unit A digital camera comprising storage means for storing.

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